PhD Dissertation Defense - Royale Hardenstine

Nov 11 2020 01:00 PM - Nov 11 2020 02:00 PM

TITLE: Spots and Sequences: Multi-method population assessment of whale sharks in the Red Sea

PRESENTER: Royale Hardenstine

ADVISOR: Professor Michael Berumen

DATE: Wednesday, November 11, 2020

TIME: 1:00 pm - 2:00 pm


ABSTRACT: In 1938 Dr. Eugene Gudger concluded of the Red Sea that “whale sharks must surely abound in this region.” Seventy years later multi-method research began on a whale shark (Rhincodon typus) aggregation near Al Lith, Saudi Arabia. However in 2017 and 2018 a dramatic decline in encounters at this site drew questions about the future of the aggregation and overall whale shark population trends in the region. In this dissertation, I describe and discuss the two year decline in encounters and show that neither remotely sensed sea surface temperature nor chlorophyll A concentrations were significantly different in seasons with or without sharks. Citizen science based photo identification was used to characterize the northern Red Sea population, the Red Sea population as a whole, show limited crossover within the basin, and connections with the aggregation in Djibouti. Scarring rates within the Red Sea are compared to recent global studies and  found the Red Sea uniquely had no predator bites observed, suggesting boat collisions are likely the main cause of major scars. Finally, building upon previous genetic work comparing Red Sea and Tanzanian sharks using microsatellites, the mitochondrial control region was sequenced and two global haplotype networks were produced and compared to each other and previous work. The stability of genetic diversity within the Al Lith aggregation is described and compared to declines previously measured in Australia. As tourism develops along the northern Saudi Arabian coast and citizen science increases in the Red Sea population dynamics within the region could be better understood. The genetic connectivity of Red Sea whale sharks to the Indo-Pacific population exemplifies the need for continued collaborative research beyond local aggregations and multinational conservation measures.

BIO: Royale is originally from a small town located in Pennsylvania in the US. Her passion for the ocean led her to pursue her undergraduate degree at the University of New England, Biddeford, Maine (USA).  During her time there, a semester abroad spent in Tanzania got her interested in whale shark aggregations and eventually led her to study whale sharks at KAUST. She completed her Master's degree at KAUST in 2015 on whale shark population genetics and remained in the Reef Ecology Lab for her PhD studies. Her broad research interests focus on whale shark aggregations and ecology. This involves working with photo identification of whale sharks from the aggregation found in Al Lith, Saudi Arabia and throughout the Red Sea. She was involved in Global FinPrint surveys in the Red Sea and has also enjoyed participating in outreach to the KAUST community, school, and local dive groups.